One verse

Srimad Bhagavatam 11.10.12

11.10.12

आचार्योऽरणिराद्य: स्यादन्तेवास्युत्तरारणि: । तत्सन्धानं प्रवचनं विद्यासन्धि: सुखावह: ॥ १२ ॥

ācāryo ’raṇir ādyaḥ syād ante-vāsy uttarāraṇiḥ tat-sandhānaṁ pravacanaṁ vidyā-sandhiḥ sukhāvahaḥ

ācāryaḥ
the spiritual master
araṇiḥ
sacred kindling wood used in the sacrificial fire
ādyaḥ
held beneath
syāt
is to be considered
ante-vāsī
the disciple
uttara
at the top
araṇiḥ
kindling wood
tat-sandhānam
the stick in the middle, which connects the upper and lower wood
pravacanam
instructions
vidyā
transcendental knowledge
sandhiḥ
like the fire, arising from the friction, that spreads throughout the firewood
sukha
happiness
āvahaḥ
bringing

The spiritual master can be compared to the lower kindling stick, the disciple to the upper kindling stick, and the instruction given by the guru to the third stick placed in between. The transcendental knowledge communicated from guru to disciple is compared to the fire arising from the contact of these, which burns the darkness of ignorance to ashes, bringing great happiness both to guru and disciple.